The light emitting theorem and structure of the light-emitting diode (LED) are different from the traditional light source. It has advantages such as less power consumption, longevous, short warming time, fast response speed, and small volume, vibration resistance, suitable to mass production, easy to satisfy the requirements of applications to produce tiny or array device. LEDs have been adopted widely in the market such as optical display device, laser diode, traffic signal, data storage device, communication device, illumination device, and medical treatment device.